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POWDER COATING, November 2018 25 could try the partial bake method to see what happens. I don't have a good answer for you because I've never sprayed these types of powder coatings. You might try adjusting the voltage on the second pass because of the insulat- ing factor from the first coat. —G.T. A manual for powder formulation and production Q Where can I get a powder production process manual? What is the most recom- mended warehouse storage tempera- ture? J.E., Apodaca, Nuevo Leon, Mexico A Several universities offer sym- posiums on the formulation of powder coatings and the operation of powder processing equip- ment. However, I don't know of any handbooks on the subject. There is a white paper available from Bruno Fawer, associate consultant at Powder Coating Consultants, that may shed some light on your questions. You can request a copy by emailing pcc@pow dercoat.com. As for the best storage temperature for a warehouse containing powder coat- ings, I recommend 70°F to 80°F for most normal formulations. Higher re- active systems (low-temperature-cure powders) should be stored at 60°F to 70°F. —N.L. Powder coating a natural gas regulator system Q I'm looking for ways to powder coat a natural gas regulator system. The black steel pipes I'm going to coat are above ground and are exposed to all the ele- ments. How effective would a powder coating be exposed to chemicals such as WD-40, Liquid Wrench, hand cleaners, and different greases? The pipes will also be exposed to heavy con- structive wrenching. If there is chip- ping, can the pipes be coated over with regular enamel paint? If corrosion occurs, will the powder coating bubble and peel off? Can the pipes be sand- blasted, or do they need to be stripped? A.S., Las Cruces, N.Mex. A Most, if not all, of the under- sea pipelines are powder coated. The Alaskan pipeline is powder-coated. It's my understand- ing that all of it was coated with an epoxy, which can withstand most chemicals, even acids, and other abuses. Film thickness is a factor that will aid in substrate protection. Clean- ing the pipe before application of the powder is critical. Improper cleaning will lead to chipping, and the wrench- ing won't help. You can touch up with a good epoxy liquid in small areas. Pipe for the Alaskan line was coated years before the pipe was installed, and as far as I know the coating has performed as specified. One negative with epoxies is their lack of resistance to ultraviolet light. In Las Cruces, you will have 360 days of sun- shine, which will likely cause the coat- ing to chalk. This is not harmful. It's the coating's way of protecting itself. But you'll be able to see the chalking quite easily. Be prepared with an an- swer when some municipal official complains about the way the pipe appears. —G.T. Eliminating contaminants from aluminum parts Q We cut, drill, and buff extruded aluminum parts in a variety of shapes in-house and then powder coat them. We've had a higher number of rejects than usual lately because of aluminum chips on the parts. We paint a lot of metallic and mica powder. We installed bag fil- ters and 250-micron filters in screens, but we still see aluminum chips on the parts (under and over the paint). We noticed aluminum flakes and other airborne dirt floating in the cure oven. The aluminum chips show up only on aluminum parts and not on steel parts. What do you recommend we do to determine the cause? Is it coming from the wash, the spray-gun tip, or oven airflow or vibration? K.M., Holland Landing, Ont. A C o n t a m i n a n t s i n p o w - der-coated products can c o m e f r o m n u m e r o u s sources. Looking at your coated and cured products will help identify what POWDER COATING pcoating.com Search Article Archives Weekly Questions and Answers Subscribe Industry Events and Updates Check out our new website on the go